did you have a dinner ? , have you had a dinner ?
what's the difference between :
1-did you have a dinner
2-have you had a dinner

and

what's the difference between :
1-I saw this movie
2-I have seen this movie

Question

did you have a dinner ?  , have you had a dinner ?
what's the difference between :
1-did you have a dinner 
2-have you had a dinner

and

what's the difference between :
1-I saw this movie
2-I have seen this movie

Answer

Here are some conversations to illustrate the difference:

1.
A:  I went to the Ritz Hotel last night.
B:  Really, did you have dinner there?
A:  No, I just had some tea.

This is talking about a past time.

A:  Have you had dinner?
B:  No, I haven't. I'm quite hungry, actually.

This is talking about the present time - you're hungry because you haven't had dinner.

2.

I saw this movie two years ago.

This is talking about past time.

I've seen this movie, so I don't want to see it again. I'd rather see another one.

This is talking about the present time - you don't want to see this movie at the moment because you've already seen it.